Operational trial of the selection cut using the 123 method

Transcription

1 580, boul. Saint-Jean Pointe-Claire, QC H9R 3J9 Operational trial of the selection cut using the 123 method In collaboration with NewPage Port Hawkesbury by Dave Lepage Philippe Meek June 2011 Page 1 RI-2008-

2 Introduction The social license to conduct efficient forest ing operations often depends on the capability to avoid clearcutting. In recent years, the FPInnovations research program allowed variations of partial cuts that meet sophisticated silvicultural objectives to be developed at a reasonable cost. Among them, the selection cut using the 123 method was developed to allow ing operations under the concept of a perpetual forest cover system. This method meets the uneven-aged management regime requirements because it permits the three basic silvicultural functions ing, tending, and regenerating in one operation. Application of the selection cut in softwood forests using the 123 method developed by FPInnovations addressed wildlife habitat concerns, maintained visual quality of highly valued landscape, and provided alternatives in ecosystem-based management schemes. As part of the FPInnovations Hardwood Initiative (improving hardwood sector competitiveness program), this project aims at giving management new opportunities when stand conditions do not meet local silviculture requirement for selection cut. FPInnovations collaborated with NewPage Port Hawksbury Operation in Nova Scotia to implement a selection cut using the 123 method. A stand mainly composed of sugar maple, located in nearby Heatherton, Nova Scotia, was selected as a replacement for a group selection cut. The latter favors yellow birch regeneration; however, this involves a large production of pulp-grade bolts in a very difficult market. A preliminary short trial was conducted in the fall of 2009, which showed that this method is efficient at keeping direct ing costs, the pulp/sawlog ratio, and growing conditions for sugar maple acceptable. Observations of the stand before and after the cut indicated that the removal can be controlled and maintain uniform. The encouraging results suggested conducting a larger trial with a significant learning period for the operators and normal variations of the stand structure. The main goals of the 2010 trials were to test the tree selection procedure, improve the stand composition, and confirm the reasonable ing costs.

3 The selection cut using the 123 method The ing method relies on three basic steps. First, the trail network is designed with future stand entries in mind. Second, the tree selection guidelines are set to meet treatment objectives in terms of removal intensity and vigor management. Third, the control procedure as part of the method is applied in order to provide rapid feedback to the operators of the felling machine. During this trial, the trail width (5 m) and the trail spacing (30 m) were set to meet the ing equipment specifications (Figure 1). The removal of trees in the trails was 100%. There was no room for tree selection, thus no stand improvement is expected from this felling except from the crown release of the nearby trees. The ed trees in this area have the same characteristics as the average stems. If the trails are straight, it is easier to protect the trees along the trail. The operational challenge of maintaining the trail width less than 5 m can be met using the door system as explained in operator s guides produced by FPInnovations. In short, the door system integrates into the operator tasks the selection of areas along the trail (each 20 m in hardwood) where two trees are chosen to be protected. The manoeuvres are limited in the vicinity of the door. Beside the trail, there are two strips (the selection zones) where the operator can access the trees to be felled by fully pivoting the machine turret away from the door area. The 5-m width of the two selection zones is recommended for most felling machines as their effective boom reach is about 7.5 m, as observed during the current trials. Considering the width of zones and trails, the recommended spacing between the forwarder trail for each entry of the selection cut with the 123 method is 30 m (Figure 2). The next entry will target the 15-m wide zone left untouched at the first entry. The other entries will concentrate on the area between the first two set of trails where the regeneration developed and where mature trees are mostly located. The time proposed between two entries is the fourth of the normal rotation, the time required to produce a mature tree in consideration of the expected wood product and species. The tree selection guidelines that address the silvicultural issues of density and vigour management of the stand are flexible. the trail is cut, the operator cuts any damaged trees. In the current trials, the selection rule had two components. The first one aimed at maintaining a regular residual canopy: cut 1 tree out of two bigger 36-cm trees. The second component set a priority for the less vigorous trees according the operational tree vigour classification adapted specially for the treated block. a preliminary test, it was established that the operator did not have to the considered trees smaller than 35 cm. Their density was highly variable and led to unwanted felling.

4 Figure 1. The felling machine operates from the trail (100% removal, width=5 m) to cut in the two nearby strips (50% removal, width=5 m) the trees selected according to the priorities set for the block. Figure 2. The removal distribution for the selection cut using the 123 method. The overall removal is 32%. Removal in the selection zone and timing for entries are flexible.

5 Stand description before and after The effects of the treatment on the stand are described using two sets of sample plots. In the first set, 11 variable radius plots were established with a factor 2 prism over the 60-ha treated area. Those plots were established before the treatment and revisited after the forwarding. A second set of plots, which is part of the 123 method, was used as a control system. The 50 control plots established by FPInnovations were installed after felling in a selection zone, and they covered 100 m² where stumps and trees were tallied. Table 1 shows that the basal area was reduced by 33%, as expected. The density in term of stems per hectare was reduced by 26% and the average diameter at breast height (DBH) reduction of 7% clearly shows that the removed trees were bigger than the average stem. This is the first indication that the 123 method provides suitable control on tree removal without tree or trail marking. Table 1. Stand description before and after with the prism plots (N=11) Variable Basal area (m²/ha) Density (Stem/ha) DBH (cm) Average before Average after Harvested Difference -33% -26% -7% Table 2 shows treatment results on some of the variables measured in the control plots. The removal rate is 27% of stand density for a 34% total volume. The average ed tree volume is m³, which is 24% larger than the average stem volume for that stand. Clearcutting or any type of treatment that removes all trees on part of this stand would mean a smaller average ed tree volume of m³. It is well known that machine productivity will benefit from this.

6 Table 2. Stand description before and after with control plot (N=50) Stand description Density (stems/ha) Volume (m³/ha) Average volume (m³/stem) Average before Average after Harvested Difference 27% 34% 9% The control plots network also provides information about the ability of the operator to meet trail network requirements. As shown in Table 3, the average trail width (measured 50 times) was 5.1 m, which is very close to the targeted width of 5 m. If we accept that the trail width can be occasionally as much as 6 m, the compliance was appropriate in 96% of cases. The operator was able to reach the target and there was very little variability in terrain and trail configuration. When trails intersect heavily, the average width and terrain variation is sometimes higher. Table 3 also indicates that the average trail spacing was almost on target. With a tolerance of 4 m for spacing (26 m < spacing < 34 m), the spacing was appropriate in 84% of cases due to the use of a GPS navigation system. In the absence of such equipment, the operator had to visually gauge the spacing. Table 3. Compliance analysis for trails Average width (m) 5.1 Right width (%) 96% Average spacing (m) 28.7 Right spacing (%) 84%

7 Figure 3 shows the trail network established by the feller-buncher after the installation of the GPS tracking device. The trail spacing is regular as permitted by the easy terrain. This is typically an area that can be treated during night shifts when the navigation system is active. Figure 3. The GPS tracking device shows the trail network established by the feller-buncher. The comparison of the stand before and after treatment allows for a more complete analysis using the computed indicator. The trees were graded using the Grading standing hardwood trees in Nova Scotia. Table 4 describes the distribution of the basal area among the four grade classes. The treatment did not reduce the proportion of the G3 (potential for the lowest quality of sawlog) and G4 (pulpwood potential) in the stand. The switch towards a higher overall tree quality is more discreet because a large share of the stand is composed of small trees of those classes. The selection guidelines do not intend to this type of tree but aims for the removal of big mature trees with defects. The reduction of the G2 proportion and the proportional increase of the G1 indicate that the 123 method indirectly improves the overall quality of the stand.

8 Table 4. Proportion in percentage before and after ing for the indicator Nova Scotia quality index Nova Scotia quality index Total Statistical estimator g1 g2 g3 g4 Average basal area (m²/ha) Proportion before and after ing (%) 8% 13% 17% 12% 25% 25% 50% 50% The operator was trained to use the operational tree classification presented in Table 5. Such classification is designed to allow the operators to easily find targeted trees. The 123 method implies that the criteria are adjusted to the treated stand during a preliminary assessment to assure the operator is not looking for rare targeted trees. For the operator, all trees fall into a two-class system: good trees without effects (Q1) or trees with defect. If a tree bares a vertical seam but the driving direction does not allow the detection, it will appear as a Q1. If the operator notices such a defect, he may consider cutting it if the priority applies. Table 5. Operational tree vigour classification (based on first 6-m stem observation) Quality 1 No major defect Quality 2 Quality 3 1 major defect on 1 or 2 faces (not always detectable from a machine cab) Stem with a major defect on 3 faces (always detectable from a machine cab): leaning, forked, crocked, spiral seam, etc. Table 6 shows that the treatment as applied during the first weeks of application resulted in an increase in the proportion of Q1 trees basal area. This indicates that the 123 method leads the operator to cut defective trees in priority.

9 Table 6. Proportion in percentage before and after ing for the indicator Operational index as sampled Statistical Q1 Total estimator Average basal area (m²/ha) Proportion before and after ing (%) 33% 38% Typically, when there is an opening in the canopy, the residual trees expend their crown and their growth may increase. Uniformly removing individual trees in the stand may be optimal but we know that this is not exactly the case with the trails cut and a 15-m wide strip left untouched with the 123 method. One more indicator helps to establish if the growing conditions have improved in the stand. A crown release variable uses a five-class system that considers that any tree may have four neighboring trees with crown competition. Table 7 indicates that a closed canopy before treatment means 67% of trees have 4/4 crown competition, 25% have a missing neighbor, and 8% have at least 2 missing neighbors with space large enough for crown development. The treatment changed the proportion and only 38% of trees did not receive a share of the crown release. Twenty-five percent of the basal area is composed of trees that have plenty room for growth. Table 7. Proportion before and after treatment of the crown release classes Statistical estimator Crown release class (missing neighbor) 0 1 2,3,4 Total Average basal area (m²/ha) Proportion before and after ing (%) 67% 38% 25% 38% 8% 25%

10 Table 8 presents the combination of Table 6 and Table 7. Trees of the vigor class 1 (Q1) showed improved growing conditions. the treatment, 23% of the basal area was composed of Q1 trees that lost at least 1 neighbor. This represents only 71 trees per ha as these are among the trees with a big diameter. If a crown release is considered with 2 missing neighbors, 11% of the basal area of the residual stand is composed of Q1 trees. The selection cut using the 123 method after one entry improved the growing condition of the best trees in the canopy. The proportion almost doubled for the ¼-crown release criteria and doubled for the 2/4-crown criteria despite a 34% removal not uniformly distributed. If such a status lasts and if a second entry gives the same results for the untouched strip of the stand, the selection cut method will become very competitive in managing the hardwood stands. Table 8. Proportion of the stand composed of best vigor and best growing conditions Q1 and ¼ or more crown release Q1 and 2/4 or more crown release Statistical estimator stems/ha % BA stems/ha % BA Average before % 4 4 % Average after % 20 11%

11 Productivity and cost The system during the selection cut trial was a 3-machine cut-to-length system with a fellerbuncher, a processor, and a forwarder. The work of each machine is described with the results of the various time studies. Table 9 shows the results of the studies of the feller-buncher operating during the first week of the implementation and after two weeks. During the second study, the average volume per ed tree was smaller than during the first week by 20%. This reduced the productivity in terms of m³/pmh despite the fact that the number of stems felled per hour increased by 10%. Under a clearcutting treatment, such an increase in stem productivity would be normal. It shows that the operator was already productive during the first days with the new selection cut using the 123 method. Overall the costs are very competitive. The time distribution among the detailed time elements indicates the 123 method is more efficient than the conventional single tree selection with tree marking as practiced in the Ottawa river valley (QC and ON). During the second study, the smaller trees were cut faster but bunching took longer, having more than 1 tree per bunch. Table 9. Productivity and cost for the feller-buncher Tigercat 845B Item description Study 1 Study 2 Study duration (PMH) 7,7 7,4 Average ed volume (m³/stem) ,274 Trees/PMH m³/pmh ,4 Direct operating cost ($/PMH) $ Felling cost ($/m³) 2.08 $ 2.40$ Work cycle elements % % Move 39% 40% Brush 14% 11% Cut 29% 22% Move to bunch 2% 1% Arrange logs 1% 1% Bunch 9% 19% Operational delays 5% 2 6% Total 100% 100% 1 Cost including direct operational cost 2 Adjusted operational delays

12 Table 10 presents the results of the short time study of the processor working along the trails set by the feller-buncher. The trees were bigger than the average stem observed in the stand. The work performed by this machine is not really different than when processing another type of partial cut where the trees are selected individually. We can expect that the relation tree size and productivity would not be affected. The detailed time distribution among the work cycle elements does not show an exceptional profile. The productivity is 20.1 m³/pmh and the estimated felling and processing cost is $6.43/m³. Table 10. Productivity and cost for the processor Item description Study 1 Study duration (PMH) 3,4 Average log volume (m3) 0,075 Average ed tree volume (m3) 0,330 Trees/PMH 61 m3/pmh 20,1 Direct operating cost ($/PMH) 1 $ Felling and processing cost ($/m3) $6.43 Work cycle elements % Move 10% Load 23% Arrange pile 1% Process 62% Operational delays 4% Total 100% 1 Cost including direct operational cost The results of the forwarder time study are presented in Table 11. The 9 trips in the study allowed for an average volume per load of 13.6 m³. The productivity is 19.8 m³/pmh for an estimated cost of $5.15 /m³. There is no special comment from the detailed time elements.

13 Table 11. Productivity and cost for the forwarder Item description Study 1 Trips 9 Study duration(pmh) 6,2 Average volume(m³/log) 0,088 Average volume per cycle 13,6 Productivity (logs/pmh) 225 Productivity (m³/pmh) 19,8 Costing ($/PMH) 1 $ Costing ($/unit) $5,15 Work cycle elements % Travel empty 6% Maneuver 5% Load 36% Move loaded 11% Travel loaded 8% Unloaded 28% Operational delays 5% Total 100% 1 Cost including direct operational cost Table 12 shows a total direct cost of $15.20 /m³ including the contractor profit margin. This is a very competitive roadside cost considering the average tree size, which is modest for hardwood procurements. The trial results show that the selection cut using the 123 method can be used to manage hardwood forests. The costs and the effects on the stands may vary with changing conditions. Only extensive implementation with some appropriate documentation would allow to define the best opportunities. Table 12. Productivity and cost related to partial cut treatment Machine m³/pmh $/m³ Feller Buncher Processor at the stump Forwarder % other contractor cost, risk and profits Total

14 Appendix 1 Processor Forwarder Feller-buncher Tigercat 845B/GNRoy Tigercat 845B/LogMax7000 Tigercat 853/Quadco INPUTS Expected mach life (years) Sched mach hours/ year Purchase price ($) Salvage value ($) Licence cost ($/yr) Insurance ($/yr) Interest rate (.%) 10% 10% 10% Utilization (.%) 85% 80% 85% Lifetime repair Costs ($) Fuel consumption (l/pmh) Fuel price ($/l) Oil and Lubrication ($/pmh) Operator Wages ($/SMH) FIXED COST Annual Capital Cost $ $ $ Yearly Other Costs $ $ $ Yearly Total $ $ $ Costs Per PMH $34.55 $42.51 $33.96 Costs Per SMH $29.37 $34.00 $28.87 VARIABLE COST Yearly Costs $ $ $ Costs Per PMH $62.47 $61.94 $44.53 Costs Per SMH $53.10 $49.55 $37.85 LABOUR COST Cost Per Year $ $ $ Costs Per PMH $23.53 $25.00 $23.53 Costs Per SMH $20.00 $20.00 $20.00 TOTAL COST Grand Total Per Year $ $ $ Grand Total Per PMH $ $ $ Grand Total Per SMH $ $ $86.72